Tiller a R/D trilam check

[l979]

Hello there,
Got this Maple/cherry/maple i need to get done asap. Never made one before and wanted to ask for advice early in the tillering process. How's it looking so far? I feel like I should work the mid limbs a bit more next and leave the fades for now, would that be correct?
If someone is sitting on a picture of what tiller i should aim for please post it, it would help out a lot.
Also what is the thinnest the belly lam or back can be?
Stats are 68", 10" riser, 1 3/4 wide at the fades out for about 8" then going to 1/2 tips.
 Hoping to get 50#/28".


 
 

[Wolftrail]

Cannot judge it untill full draw.  But you have to be careful in the fade area, looks like not much meat there.

[takefive]

I can't tell this early in the process while it's still on the long string.
Here are some pictures of the last one I made:

 http://tradgang.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=125;t=013286;p=1#000000

Maybe Roy will chime in.  He's got tri-lams down to a science.

[Bowjunkie]

Why do the outer limbs look so thick? I would not remove any wood from the mid limb at this point.

We need to see a front profile picture before we offer any tillering advice.

[l979]

Wolftrail: Yeah I don't have much to play with on the thickness, I've had to take some width off to get the weight down.

takefive: Aw that's nice! I'd be really happy to get a nice bend like that. Thanks for posting it, it makes it much easier to have something to aim for.

Bowjunkie: They look thick because they are, I wanted to wait to work on them until i get closer to the end. I'm afraid I take to much off there to early and I'll end up with a light weight. And I posted a front profile picture.

This is where I  was 5# ago, I have worked the the limbs a little bit since then, seemed  little flat 6" out from the fades.

 
 

[LittleBen]

I think it's time to start getting those tips involved. I would narrow them carefully first, then start to remove belly wood and get em bending.

[l979]

Alright, that's how i'll proceed now. I'll post some pics soon again.

[l979]

Something came up while tillering. I was told to make the bow symmetrical and put the shelf 2" from center. Now when I pull the string the lower limb bends much less and to make the bow to bend evenly
 I'd have to make the the lower limb weaker then the upper but then the bow is uneven at brace. Am I doing this right? Also would cutting the  lower limb an inch or so remedy my problem?

[mikkekeswick]

You can make the limbs the same length and center of the bow is the center of the handle or indded make the lower limb an inch shorter at this stage you are fine to do either. Shorter lower limb simply carries a bit better in the hand due to the weight distribution.

Forgot this mentality of work on this bit, then work on that bit etc....
Your goal right now is to get perfect tiller on the WHOLE limb. Once you have it correct then it is simply a case of even wood removal to get the weight where you want it.
Make sure you are pulling it to intended final draw weight the whole time unless you spot a problem area then you would fix that area and aim to get back pulling full weight asap.
Your tiller looks pretty good at this point. It is definitely possible to determine the tiller when only pulled this far. It is a thing that you develop an 'eye' for.

[Roy from Pa]

Bowjunkie: They look thick because they are, I wanted to wait to work on them until i get closer to the end. I'm afraid I take to much off there to early and I'll end up with a light weight.

You should have had those limbs thickness tapered even before glue up. You should have floor tillered the bow before placing it on the tree, to get some bend in them. Look how flat the outer portion of the limbs are, as they would be since they are so thick. They should already be bending some. Looks like the limbs are bending a lot right outside the fades. I would reduce the thickness on those outer limbs before going any farther.

The tiller right now resembles how a d/r bow will look this early on, however you need to thin down the outer 1/3 of the limbs.

[Bowjunkie]

Yep, what Roy said. That's what I was getting at. And in accordance with the limb front profile picture you posted, the limbs shouldn't get thicker heading toward the tips. Perhaps a tiny bit in the last couple of inches if you're going to narrow them there to reduce tip mass, but not half of the limb. You run the risk of overworking the inner limbs, which is the worst place to induce set because a little bit of set there projects out to a lot at the tips.

Before I even put such a bow on the tillering tree, I have it evenly tapered in thickness from dips to tips... heck, to be honest, I have things tapered before glue up. It's not necessary, but it eliminates some hurdles that pop up on occasion.

As far as relative limb strength, yes, you will need to make the bottom limb weaker to balance them if you put the shelf 2" above bow center and shoot split finger.

If you make the bottom limb shorter, you might be ok with an even tiller, but I would let the tillering tree tell me exactly what it needed. Hold it on the tree and pull the string where you will while shooting it, and balance the strength of the limbs so the hook comes straight down the wall.

[l979]

I've only made d-bows before so this is a different animal to me. I did taper the core lam 1/4" to 1/8", fades to tip, back lam 1/8" non tapered and belly 1/4" non tapered. I've started to work the tips down, I'll see if I can get a pic in before work.
Btw, so are your outer third about the same thickness as your inner third?

[Roy from Pa]

From Bowjunkie:

If you make the bottom limb shorter, you might be ok with an even tiller, but I would let the tillering tree tell me exactly what it needed. Hold it on the tree and pull the string where you will while shooting it, and balance the strength of the limbs so the hook comes straight down the wall.

X's 2

Thin the limb thickness where it's marked.
I make my belly lam 1/4" parallel.

[l979]

Did some work on the tips, I didn't think I could go so thin on them before they'd start working. Unfortunately I had some family emergency so I won't be able to work on it for some time, I'll be back.

[l979]

Hello again,
Alright, I had to go back to Sweden to help out my family but I'm back and did some work on the bow  last night. I'm at 16" going to 27".
Looking better? Maybe still a bit stiff on the left?